Investigating the scientific obstacles to quantum computers, cryptography and teleportation

2/9/2012

Researchers are on the cusp of momentous research breakthroughs in quantum systems; however, quantum decoherence due to environmental noise is a major obstacle to technological advancement. Funded by the Air Force Office of Scientific Research (AFOSR), Dr. Ting Yu, Professor in the Department of Physics and Engineering Physics at Stevens, and his collaborator, Professor Joseph H. Eberly of the University of Rochester, are at the forefront of this struggle to control quantum entanglement by developing new error correction codes for thermal, colored and correlated noise interference.

“This grant from the AFOSR highlights the tremendous impact of Dr. Yu’s collaborative research,” said Dr. Michael Bruno, Dean of the Charles V. Schaefer, Jr. School of Engineering and Science. “Dr. Yu is working at the vanguard of this field to make quantum technology a reality. His work will pave the way for radical technological advancements in both the computer and communication industries.”

A hypothetical quantum computer could for instance process large numbers at such a speed that the heavily encrypted codes that protect the most world’s sensitive information could be cracked in a matter of months rather than the century it would take using conventional methods. Beyond the potential power and speed, quantum systems can also detect intrusion. In a classical system, the sender and receiver of an electronic transmission have no way of knowing whether a third party has eavesdropped on the signal. In a quantum system the eavesdropper alters the quantum state of the particles he or she intercepts. Thus, the change in quantum state can subsequently be detected by the receiver, opening the door to technological advancements in security systems and devices.

The control of quantum entanglement is vital to the potential benefits of quantum information science. In a classical system, information is stored in the two positions of an electrical switch. In a quantum system, information can be coded in the shared quantum state of particles that are “entangled.” However, environmental noise during transmission can interfere with the system to cause various physical processes such as dissipation, fluctuation, de-coherence and disentanglement. Avoiding the loss or corruption of information during transmission is vital to developing useful quantum devices and is largely dependent upon how well researchers can control or mitigate quantum disentanglement.

Researchers in the field have thus far successfully controlled amplitude and phase damping noises that cause disentanglement. Yu and Eberly’s investigations are now furthering science to advance the control of quantum entanglement to thermal, colored and correlated noises that simulate a more realistic environment and bring quantum computing closer to realization. Yu expects that an essential research breakthrough is imminent. He envisions the twenty-first century as a truly quantum era, in which quantum technologies enable unconditionally secure communication and faster computation.

“It’s stunning to think that 25 or 30 ago no one thought this was possible,” said Yu. “But as a result of ambitious collaborative research we stand close to realizing a powerful tool from a promising theory.”

Yu’s group at Stevens has established numerous fruitful collaborations with theorists and experimentalists from around the world. In addition to Eberly’s group, Yu and his team has worked with Dr. Bei-Lok Hu’s group at the University of Maryland, Dr. Z. Ficek’s group at KACST, Saudi Arabia, and Dr. J. Q. You’s group at Fudan University, China.

Yu established the Quantum Information and Quantum Optics Group at Stevens in 2008 with the goal of understanding and implementing quantum entanglement in various information processing tasks. In 2008 the National Science Foundation awarded him a grant to study quantum dynamics of AMO systems and non-Markovian quantum trajectories for many-body systems, and in 2009 the Defense Advanced Research Projects Agency (DARPA) awarded him a grant to study the entanglement dynamics of qubit systems.